Mating habits of common rats

The brown rat, also known as a Dallas sewer rat, or Norway rat has a tiered social system similar to that of dogs and large cats in that the biggest and fittest males are dominant and get the females. Brown rats will breed year round and each female can produce four to six litters a year. Texas rats are not monogamous so a male will impregnate as many females as possible at one time. The rat’s gestation period is a short twenty one days, and the female gives birth to seven to fourteen young each time.



Brown rats reach sexual maturity in a short five to seven weeks and then they start breeding. If conditions are right, the mischief (yes that is what you call a group of rats), could feasibly increase its number by four times in just a few months! This rat’s life span is up to three years and it can breed for the majority of its life. Because of the Texas brown rat’s social hierarchy, if food or water becomes in short supply, the first rats to go are the ones on the bottom of the totem pole. The superior rats will then redouble their efforts to breed and increase the population.

The Dallas black rat, or Dallas Ship rat, or roof rat has mating habits that are similar to the brown rat with a few key differences. Like the brown rats they form groups called a mischief and the dominant male gets the most females. Females are far more aggressive that the males and WANT to breed with the best male. Within any groups there will always be one or two dominant females. In the wild their breeding period is seasonal, restricted by the availability of food, water, and adequate shelter. In a natural habitat the Texas black rat will only breed late summer through early fall producing just one or two litters per year. In urban areas were food and shelter is more constant the black rats will breed year round and the females will have three to six litters per year. After a short twenty one day gestation period the female will give birth to five to ten young, who will stay with her till they are about three weeks of age. The young rats can now eat and fend for themselves, but black rats do not sexually mature until they are around Twelve weeks of age. These rats like most types of rodents all engage in inbreeding, and polygamous sex.

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